Convergence insufficiency occurs when your eyes don't work together while you're trying to focus on a nearby object. When you read or look at a close object, your eyes need to turn inward together (converge) to focus. This gives you binocular vision, enabling you to see a single image.

Convergence insufficiency can cause difficulty with reading. This may make parents or teachers suspect that a child has a learning disability, instead of an eye disorder.

Treatments for convergence insufficiency are usually effective.

Not everyone with convergence insufficiency experiences symptoms. Signs and symptoms occur while you're reading or doing other close work and may include:

Eyestrain

Headaches

Difficulty reading — words blur or seem to move on the page

Double vision

Difficulty concentrating

Squinting or closing one eye

When to see a doctor

If you or your child experiences signs and symptoms of convergence insufficiency or has problems reading, consult an eye care professional, such as an ophthalmologist or an optometrist. A technician called an orthoptist may help with the evaluation and treatment.

Convergence insufficiency results from misalignment of the eyes when focusing on nearby objects. The exact cause isn't known, but the misalignment involves the muscles that move the eye. Typically, one eye drifts outward when you're focusing on a nearby word or object.

Difficulties with reading and concentrating can adversely affect a child's learning. Convergence insufficiency typically isn't detected in routine eye exams or school-based vision screenings. A child with the condition may be evaluated for learning disabilities because of his or her reading troubles.

Convergence insufficiency may not be detected during a routine eye exam. To diagnose the condition, your eye doctor may do the following:

Take a medical history. This may include questions about problems you have with focusing, blurred or double vision, headaches, and other signs and symptoms.

Test your eyes' ability to focus. This is done with simple tests, such as asking you to focus on a small object while it's slowly moved toward you or to read an eye chart through a prism lens.

Perform a routine eye exam. If you have any other vision problems, such as nearsightedness, your eye doctor may conduct tests to assess the degree of the problem.

Treatment options for convergence insufficiency include:

Pencil pushups. In this simple exercise, you focus on a small letter on the side of a pencil as you move it closer to the bridge of your nose, stopping the movement if you have double vision. Your doctor may suggest you do this at home for 15 minutes a day, five or more days a week.

Office or home-based vision therapy. You can do eye-focusing exercises to improve convergence. If you do this at home on a computer, you can print your results to share with your eye doctor.

Combined therapy. Many experts recommend using vision therapy — often with computer software programs — along with pencil pushups. The combined approach may be more effective. And the computer-assisted therapy may be more engaging for children.

Reading glasses. If computer therapy or exercises don't help, your doctor may suggest you use glasses with built-in prisms for reading. This is usually more effective for children.

Continued observation. It's possible to receive a diagnosis of convergence insufficiency but not show any signs or symptoms. If this is true for you, watch for symptoms when you're reading or doing close work. Your doctor may want to retest you sometime in the future.

Studies show that vision therapy at a doctor's office is more effective than doing eye exercises or computer-assisted therapy at home. Other aspects to consider before choosing a treatment are cost and convenience.

You will likely see improvement in your symptoms after four weeks of doing exercises or computer-assisted therapy. Treatment can offer long-standing relief of the symptoms of convergence insufficiency. But symptoms may come back:

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